Chest CT accuracy in diagnosing COVID-19 during the peak of the Italian epidemic: A retrospective correlation with RT-PCR testing and analysis of discordant cases. Issue 130 (September 2020)

• Record Type: Journal Article
• Authors: Falaschi, Zeno; Danna, Pietro S.C.; Arioli, Roberto; Pasché, Alessio; Zagaria, Domenico; Percivale, Ilaria; Tricca, Stefano; Barini, Michela; Aquilini, Ferruccio; Andreoni, Stefano; Carriero, Alessandro
• Is Part Of: European journal of radiology. Issue 130(2020)
• Publication Date: 2020-09
• Subjects: Sars-Cov-2 severe acute respiratory syndrome coronavirus 2 -- COVID-19 Coronavirus Disease 2019 -- RT-PCR real-time reverse-transcriptase-polymerase chain reaction -- ED emergency department -- PPV positive predictive value -- NPV negative predictive value -- TP true positives -- FP false positives -- TN true negatives -- FN false negatives -- COPD chronic obstructive pulmonary disease -- CHF congestive heart failure; COVID-19 -- Sars-CoV-2 -- Tomography -- X-ray computed -- Diagnostic X-ray radiology; Medical radiology -- Periodicals; Radiology -- Periodicals; Radiologie médicale -- Périodiques; Medical radiology; Periodicals; 616.075705
• DOI: 10.1016/j.ejrad.2020.109192
• Languages: English
• ISSNs: 0720-048X

Abstract

Highlights: In our experience chest CT had a significantly higher specificity and accuracy in detecting COVID-19 pneumonia than previously reported. Chest CT and RT-PCR positive rates were 485/773 (62.7 %) and 462/773 (59.7 %), respectively. CT sensitivity and specificity for COVID 19 with RT-PCR as reference were 90.7 % and 78.8 % respectively. CT PPV, NPV and accuracy were 86.4 %, 85.1 % and 85.9 % respectively. Abstract: Objectives: The goal of this study was to assess chest computed tomography (CT) diagnostic accuracy in clinical practice using RT-PCR as standard of reference. Methods: From March 4th to April 9th 2020, during the peak of the Italian COVID-19 epidemic, we enrolled a series of 773 patients that performed both non-contrast chest CT and RT-PCR with a time interval no longer than a week due to suspected SARS-CoV-2 infection. The diagnostic performance of CT was evaluated according to sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and diagnostic accuracy, considering RT-PCR as the reference standard. An analysis on the patients with discrepant CT scan and RT-PCR result and on the patient with both negative tests was performed. Results: RT-PCR testing showed an overall positive rate of 59.8 %. CT sensitivity, specificity, PPV, NPV, and accuracy for SARS-CoV-2 infection were 90.7 % [95 % IC, 87.7%–93.2%], 78.8 % [95 % IC, 73.8−83.2%], 86.4 % [95 % IC, 76.1 %–88.9 %], 85.1 % [95 % IC, 81.0 %–88.4] and 85.9 % [95 % IC 83.2−88.3%], respectively. Twenty-five/66 (37.6 %) patients with positive CT and negative RT-PCR results and 12/245 (4.9 %) patients with both negative tests were nevertheless judged as positive cases by the clinicians based on clinical and epidemiological criteria and consequently treated. Conclusions: In our experience, in a context of high pre-test probability, CT scan shows good sensitivity and a consistently higher specificity for the diagnosis of COVID-19 pneumonia than what reported by previous studies, especially when clinical and epidemiological features are taken into account.